DUI: reveal all items under label

State: _High_
# Preface
All members should appear after click on Group. Group should be highlighted, when mouse is over, and underlined after selection.
# Before
![image](https://cloud.githubusercontent.com/assets/8158404/4766417/3292b09e-5b50-11e4-9ffb-122c9360622d.png)
# After
![image](https://cloud.githubusercontent.com/assets/8158404/4766420/3df10d3c-5b50-11e4-8c98-40e41cee4690.png)
# Reviewers
@Benglin ,@vmoyseenko, please take a look.

Link to YouTrack:
[MAGN-4919](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4919) DUI: On clicking each of the labels of results, they should reveal all items under that label
We have to explain why ```+2``` is needed here, it is good enough a reason for us to rewrite this. Here's what I would suggest (```FullyQualifiedName``` is explained below):

```cs
// Skip past the last delimiter and get the group name.
var fullName = FullyQualifiedName;
var delimiter = string.Format(``` {0} ```, Configurations.ShortenedCategoryDelimiter);
return fullName.Substring(0, fullName.LastIndexOf(delimiter) + delimiter.Length);
```

Also, I'm wondering if we could standardize the terms we use on ```SearchMemberGroup```. Please let me know what you think about these: ```FullyQualifiedName```, ```Name``` and ```Prefix```. In this case, ```FullyQualifiedName = Prefix + Name``` on the ```SearchMemberGroup``` class. Does that make sense?